Compound refrigeration system



Feb. 15, 1966 K. QUICK COMPOUND REFRIGERATION SYSTEM 2 Sheets-Sheet 1Filed July 31, 1962 flnue nlm LESTER K. QUICK r f Feb. 15, 1966 L. K.QUICK 3,234,749

COMPOUND REFRIGERATION SYSTEM Filed July 31, 1962 2 Sheets-Sheet 2 J42umto z N LESTER K. QUICK Mia ma United States Patent 3,234,749 COMPDUNDREFRIGERATION SYSTEM Lester K. Quick, 600 Howard St., Eugene, Oreg.Filed July 31, 1962, er. No. 213,715 16 Claims. (Cl. 62-129) Thisapplication is a continuation-in-part of my copending application SerialNo. 126,471 filed July 14, 1961, for Compound Refrigeration CompressorSystem, now abandoned.

This invention relates generally to the heat pump and refrigerationarts, and more specifically to the thermocycle integration of commercialrefrigeration, air conditioning and heating systems in a permanentinstallation.

The invention further relates to a refrigeration system for a commercialinstallation such as a supermarket or the like, and more particularly toan arrangement of compressors wherein three large compressors providerefrigeration for the low temperature display and storage fixtures, thenormal or commercial temperature display and storage fixtures and theair-conditioning system; and wherein the low temperature compressordischarges its load to the normal temperature compressor, therebystabilizing the normal temperature compressor and preventing on and offcycling thereof.

In a typical conventional refrigeration system for a refrigeratingfixture, a supply of liquid refrigerant is stored in the receiver toaccommodate fluctuations in the fixture requirements for additional orless refrigerant to maintain a substantially uniform fixturetemperature. The temperature of the liquid refrigerant in the receiveris usually above room temperature, and the receiver is on the highpressure side of the system whereby the pressure causes the liquid tomove through a liquid outlet line to a refrigerant metering controlresponsive to fixture temperature for admitting refrigerant as needed toa metering device, such as an expansion valve. Such a valve metersrefrigerant into the evaporator of the fixture and reduces the pressureof the refrigerant, :the evaporator thus being on the low pressure sideof the system. Most of the refrigerant in the evaporator immediatelydownstream from the expansion valve is in liquid state, but thisrefrigerant is at a lower temperature than the refrigerant upstream ofthe valve due to the reduction in pressure. Refrigerant in theevaporator absorbs heat from the fixture and its contents in order tocool the fixture and contents, and the refrigerant is thus vaporized andsuperheated so that at the evaporator outlet it is entirely a gas. Sincethe pressure and temperature of a refrigerant vary directly in a knownrelationship, the expansion valve may be responsive to the refrigerantpressure or temperature at the evaporator outlet to assure completevaporization of the refrigerant, and the valve will open and close asrequired to maintain a proper refrigerant flow in the evaporator. Therefrigerant vapor from the evaporator outlet is drawn through a suctionline into the intake or low pressure side of a refrigerant compressorwhere the refrigerant is compressed into high pressure-high temperaturevapor (heat of compression being added to superheated vapor). The hotrefrigerant gas is discharged from the high pressure side of thecompressor into a condenser in which a heat exchange takes place withthe cooling medium causing the gas to condense or liquify, and theliquid refrigerant flows into the receiver to complete the cycle. Itwill be clearly understood by those skilled in the art that the functionof the compressor in any refrigerant system is to remove the heat-ladenrefrigerant vapor from the evaporator, to raise the pressure of thisvapor high enough to be condensed to a liquid in the condenser, and tomove the refrigerant through the entire system.

In the past the practice has been to provide independent and separaterefrigeration systems for individual refrigerated fixtures, such asstorage or display cabinets for food products, or for a small number offixtures all operating at about the same temperature to be operated byone refrigeration system (sometimes called multiplexing). Both types ofprior systems have required careful engineering design and sizing ofcomponents for the efficient operation thereof. For instance, thepurpose of any system is to maintain uniform cooling temperatures in theevaporators of the fixtures and to this end the compressor capacity mustbe balanced against the refrigeration requirements of such evaporatorsso that vapor will be removed from the suction lines at substantiallythe same rate it is produced by evaporation in the evaporators. Insingle fixture systems, on and off cycling of the compressor is anaccepted method of controlling temperature variations of the fixtureevaporator even though it is well recognized that on and off compressorcycling is not an efficient technique for compressor operation per se.In larger, multicylinder compressors for multiplexed systems havingseveral fixtures operated thereby, compressor cycling is highlyundesirable and various capacity control means of conventional andwell-known construction have been devised for sequentially orselectively disabling and enabling (unloading and loading) cylinders orotherwise varying the efiiciency or capacity of the compressor so thatrefrigerant vapor is removed from the suction lines of the fixtures atsubstantially the rate as is produced therein. Representative of suchcapacity control means is an unloader piston arrangement for holding thesuction valve of one or more cylinders in open condition therebypreventing vapor compression by the pistons in such cylinders; and otherdevices have been devised for by-passing selected cylinders as thereturning refrigerant requirements demand.

It will be understood that in stores or other installations requiringseveral of such prior systems that the duplication of compressors,condensers, and other equipment in the several systems increasedpurchase, installation, power and service costs and require a relativelylarge space for the installation. In addition, independent and separatesystems were also required for winter heating and summer cooling.

In modern large supermarkets or stores where a large number of storageand display fixtures are required for the various products requiringrefrigeration in a wide range of temperatures varying between about 20F. up to about F., the provision of numerous separate refrigerationsystems brought the cost, space and service problems into acute focusand emphasized the need for more efficient, economical and space savingrefrigeration for commercial installations.

The principal object of the present invention is to provide a singlenovel compound refrigeration system integrating the entire refrigerationand air-conditioning requirements of an installation having numerousrefrigerated fixtures by employing only three compressors and twocondenser-receiver means in a manner to assure stability and economy ofoperation, reduced costs and improved control and safety features.

Another object is to reclaim heat from the refrigeration function forutilization in building heating.

It is another feature of this invention that the airconditioningcompressor is available as a stand-by for either of the othercompressors, thereby minimizing loss of essential refrigeration in theevent of compressor failure or service needs.

It is another feature of this invention that oil entrained in therefrigerant is collected in a common oil-separator and returned to thecompressors as needed, controlled by a float switch or the like.

A still further object is to provide a common liquid refrigerant sourcefor all refrigeration fixtures, and to provide a novel arrangement offixtures to assure safe and efficient operation particularly whererefrigeration temperatures are critical.

Still another feature of the invention is to provide a novel audible andvisual alarm system to assure early warning of malfunction.

Still a further object of this invention is to provide a common liquidrefrigerant source and novel arrangement of refrigerating fixtures,whereby any malfunction in the refrigeration system resulting in aninadequate supply of liquid refrigerant in turn results first, in a lackof refrigerant available to the least critical fixture; and lastly, in alack of refrigerant available to the most critical fixture.

These and still other objects and advantages of the present inventionwill become readily apparent from the annexed specification and theaccompanying drawings.

In the drawings:

FIGURE 1 is a diagrammatic representation of a com pound refrigerationsystem embodying the invention; and

FIGURE 2 is a diagrammatic representation of a modified embodiment of acompound refrigeration system.

Referring now more particularly to FIGURE 1, of the drawings, the systemincludes a compressor 19, which is denominated herein as the standard orcommercial temperature compressor and serves to operate a bank ofrefrigerating fixtures, such as commercial or normal temperaturerefrigerators 18A through 18E operating in the range of about 25 F. toabout 50 F. The system also includes a high temperature compressor 11,which operates an air-conditioning system; and a low temperaturecompressor 12, which operates a bank of low temperature refrigerationfixtures 311A through 30F operating generally in the range from about 20F. to about 5 Ft The function of each of the individual compressors 1t11 and 12 is basically the same as their individual compressor functionin prior conventional systems. However, due to the large number offixture evaporators and the large variants in refrigerant vaporizationthereby, capacity control means for each of the compressors must becapable of maintaining the necessary balance of each compressor with thesuction side of its respective portion of the system, including theaccommodation of refrigerant vapor discharged between those compressorsin the compounded relationship hereinafter described.

The refrigerant from the standard temperature compressor is dischargedthrough conduit 13 to an oilseparator 13A and thence to condenser 14 andreceiver 15, which forms a liquid refrigerant reservoir. A liquid headeror conduit 16 is provided for feeding refrigerant through solenoidoperated valves 17 and expansion valves 17A to the individual standardtemperature refrigerating evaporators 18, and thence through suctionheader 19 and conduits 20 and 21 back to the suction side of thecompressor 10. Each fixture 18 inherently has a variable refirgerantdemand to maintain a substantially constant temperature thereof, and therefrigerant vapor return load in the suction header 19 to the compressor10 is subject to relatively large fluctuations. In comparison, thefixtures inherently provides a relatively constant refrigerant vaporreturn load in the suction header 31 to the compressor 12.

The low temperature compressor 12 has its discharge connected by conduit22 to an inter-cooler 23 and through another conduit 24 and the conduit21 to the suction side of compressor 10. As is well-known to thoseskilled in the refrigeration art, the suction pressure from the lowtemperature refrigerating fixtures will be lower than the suctionpressure from the standard temperature refrigerating fixtures and thecompressor 12 compresses the return refrigerant from the evaporators 30to the suction pressure maintained by the compressor 10. The relativelyconstant refrigerant load from the low temperature compressor 12 iscombined with the fluctuating return refrigerant load from theevaporators 18 to thereby produce a stabilizing volume of refrigerant tothe suction of the compressor 10, and this refrigerant iscompressed bycompressor 10 and discharged through the conduit 13 to the condenser 14and receiver 15. The refrigerant flow from the receiver 15 is dividedand a portion passes through conduit 25, through the intercooler 23 andconduit 27 to a liquid header 28 feeding refrigerant through solenoidoperated valves 29 and expansion valves 29A to the individual lowtemperature evaporators 30. Refrigerant then flows from the evaporators30 through a suction header 31 and conduit 32 back to the suction sideof low temperature compressor 12.

Compressor 11 discharges refrigerant through conduit 33 to condenser 34,thence to receiver 35 and conduit 36 to an air-conditioner evaporator 37and back through suction conduits 38 and 39 to the suction side ofcompressor 11. A blower 40 draws air either from within the building orfrom the outside, as controlled by louvers 41 and 42, respectively, overthe condensers 14 and 34 for removing heat from the refrigerant incondensers 14 and 34. The heated air may be discharged to the outsideair as through a duct 43 or into the building through adamper-controlled duct 44 to heat the building. The reclaiming of heatfrom the condensers for space heating within the building or likeconfined area is more fully disclosed in Quick Patent No. 2,892,324.However, in the present invention, the condenser 34 forms a supplementalair heater by operation of the air-conditioning compressor 11 as a heatpump and using an external evaporator 45 as an auxiliary heat source,whereby the refrigerant passes from receiver 35 through conduit 36 toexternal evaporator 45 and back through suction conduits 38A and 3? tothe suction side of compressor 11.

The air-conditioning compressor 11 also has a suction line 46 connectedto the suction line 39 on the downstream side of a normally open valve39A. The suction line 46 is connected to a suction header 47 extendingbetween the standard temperature suction header 19 and the lowtemperature suction header 31, normally closed valves 48 and .9preventing return flow of refrigerant vapor from the headers 19 and 31to the compressor 11. It should also be noted that a valve 50 is placedin conduit 33 and a valve 51 is arranged in conduit 52 which is incommunication With the oil separator 13A. It will be seen that byclosing the valves 50 and 39A, the air-conditioning circuit can beisolated from the compressor 11, and that by opening the valves 51 and48, the compressor 11 may be connected in the refrigeration system inplace of the standard temperature compressor 19. The compressor 10 ismade inoperative by closing the normally open valves 76 and 71 in thesuction and pressure lines 21 and 13 thereto. The air-conditioningcompressor also has similar service valves 72 and '73 on its intake anddischarge lines. Similarly, the low temperature compressor 12 has intakeand discharge control valves 74 and 75.

.A valve 53 controls a conduit 54 between conduits 33 and 22. It will beseen that by closing the valves 50 and 39A to isolate theair-conditioning circuit and closing valves 74 and 75 to isolate thecompressor 12 and by opening the valves 49 and 53, the compressor 11 maybe connected in the refrigeration system in place of the compressor 12.The chart set forth below summarizes the positions of the various valvesunder the three above described conditions of operation of the threecompressors.

Normal operatlon of all compressors Compressor 11 substituted forcompressor Compressor 11 substituted for compressor 12 Closed.

Open.

Closed.

In the oil return arrangement shown in FIGURE 1, an oil receiver orreservoir 55 collects oil from the oil separator 13A and is vented in aconventional manner by a degassing line 64 connecting the upper portionof the reservoir to the suction side of the standard temperaturecompressor 10. The oil from the reservoir 55 passes through conduit 56,valve 57, solenoid operated valve 58, float switch 59 to compressor 1tand similarly, oil is passed through lines 60 and 65, valves 61 and 66,solenoid operated valves 62 and 67, float switches 63 and 68 tocompressors 11 and 12.

The inter-cooler 23 is provided to desuperheat the refrigerant vapordischarged from the low temperature compressor 12 to preventover-heating of the compressor 10. It will be noted that the conduit 25from receiver 15 to conduit 27 and the liquid header 28 are connectedthrough the inter-cooler in a typical manner. A liquid supply line 76may also be provided to the chamber of the intercooler 23 and anexpansion valve 76A responsive to vapor pressure or temperature at theinter-cooler discharge assures proper desuperheating in the inter-cooler23.

. The refrigerated fixtures 18A through E and 30A through F arerepresentative of the different types of fixtures that may be requiredin a modern supermarket, and are not intended to be inclusive. Thefixtures are required to maintain product temperatures in a range fromabout -20 F. up to about 50 F., the standard or commercial temperaturesfixtures ldA-E being in the upper part of the range from about F. toabout 50 F. and the low temperature fixtures EiiA-F being in the lowerpart of the range from about 20 F. to about 5 F. For instance, producecases or coolers will have product temperatures at about 45 F. to 50 F.,dairy cases or coolers at about 35 F. to 40 F., and fresh meat cases orcoolers at about F. to F., all in the normal temperature range, whereasmost frozen food products will be maintained within a range of 10 F.temperature variation at about 0 F. except ice cream coolers or cases,which require a temperature of about 20 F. to keep the product firm. Itwill be apparent that several of each type of case or storage cooler maybe required and represented in the drawings by a single fixture unit.

Referring now to FIGURE 2 of the drawings, liquid refrigerant stored inthe receiver 15 flows through the liquid header 16 to each of theexpansion valves 17A of the standard temperature evaporators 18 andthrough the liquid header 28 to the expansion valves 29A of the lowtemperature evaporators 30. In this embodiment of the invention, theliquid headers 16 and 28 are combined as one continuous header, showngenerally at 80, extending from its upstream end 81 connected to thereceiver 15' to its downstream end 32 connected to the last lowtemperature fixture 36F. The evaporators 18 of standard temperaturefixtures ISA-E are connected to the header portion 17 by supply lines83-87, respectively, and the evaporators of low temperature fixtures30A-F are connected to the header portion 28 by supply lines 88-93,respectively. The solenoid valves 17, 29 and expansion valves 17A, ZfiAare connected in the supply lines and to the evaporator inlets in ausual manner. The header 80 is sized to accommodate the totalrefrigerant requirements of the fixtures and, as long as a supply ofliquid refrigerant is maintained in the receiver 15, the inherentpressure of the liquid refrigerant will cause it to flow downstreamthrough the header to maintain the supply lines to all of the fixturesin a liquid filled condition to meet the demands of the various fixturesfor refrigera tion. Due to the inertia of the liquid refrigerant flow,the refrigerant will tend to flow to the downstream end 82 first andpile up so that any refrigerant vapor in the header will be excludedfrom the downstream end 82 by liquid refrigerant. The presence ofrefrigerant vapor in the header 30 would normally occur either whenrefrigerant demands are high and the receiver 15 is emptied or when arefrigerant loss occurs in the system.

In the event of such loss, or unusually high demand, the liquidrefrigerant flow from the condenser 14 through the receiver 15 into theheader 80 will fill the downstream end 8.2 of the header portion 28 andcreate a pseudo liquid level somewhere along the header, depending onthe quantity of liquid present at any time. Due to inertia and thepiling up effect, the surface of the pseudo liquid level would beinclined to both the vertical and horizontal. It will be noted that theliquid header 8%) is shown in a vertically inclined position slopingdownwardly from the upstream end 81 to the downstream end 82, and thisis a preferred physical arrangement as the gravitational force adds tothe refrigerant flow inertia to create an even more distinct pseudoliquid level.

If a. small loss occurs and the pseudo level is to the left of thesupply line 83 to the standard temperature fixture 18A liquidrefrigerant will continue to be supplied to all fixtures for normaloperation. However, if the liquid refrigerant being supplied to theheader 8% is insufficient to balance the liquid refrigerant demand by al of the fixtures, the pseudo liquid level will begin moving fromupstream end 81 toward the downstream end 82. Alarge loss or lack ofliquid refrigerant would result in refrigerant vapor being present inthe supply line 83 and possibly additional successive supply lines,whereby the evaporators connected thereto will cease to cool properlywhen the residual liquid therein has boiled away.

A feature of the invention is the provision of audible and visualwarning means for indicating a loss of liquid refrigerant to theupstream supply lines 83 and 84. The visual means comprises a sightglass 94 positioned in each of the upstream supply lines 83 and 84 bywhich the presence or absence of liquid refrigerant may be observed. Theaudible warning device comprises an alarm 95 with a relay 96 forenergizing same. The relay 96 is controlled by temperature responsiveswitch elements 7 in the fixtures 18A and 1813 or by temperature orpressure switch means in the evaporators 18 for these fixtures. Upon anundesirable temperature increase in both fixtures 18A and 183 at thesame time, the relay 96 will be closed to activate the alarm 95. Theswitch means 97 are connected in series to prevent false alarms duringthe defrost cycles of either fixture, and the fixture defrosts are timecontrolled to prevent simultaneous defrosting. The switches 97 are alsoresponsive to a higher temperature than would occur during normalcooling and non-cooling cycling of the evaporators 18.

In order to insure that the refrigerated fixtures that are operated atthe lowest temperatures and contain the most temperature-changesensitive products have all of the liquid refrigerant present in thesystem available for their evaporators, the supply lines to theseevaporators are connected to header 80 near the downstream end 82.Conversely, the fixtures that operate at the highest temperatures andcontain products that are not extremely sensitive to temperature changeshave their evaporator supply lines connected to header 80 near theupstream end 81. Thus, as described above, if there is an inadequatesupply of liquid refrigerant and the pseudo liquid level in header 80moves from left to right toward end 82, then the highest temperaturefixtures will be the first to have an inadequate supply of refrigerantand the lowest temperature fixtures will be the last to be effected bythe lack of liquid refrigerant. In accordance with this plan ofarrangement, a preferred installation would be; produce case 18A,produce cooler 18B, dairy case or cooler 13C, fresh meat case or cooler18D, fresh meat cooler 18E, smaller frozen fish cases 30A, frozen meatcase 3013, frozen fruit and vegetable cooler SiiC, frozen fruit andvegetable case 30D, ice cream cooler 3GB and ice cream case 30F.Additional or similar cases or coolers would be arranged in the same orsimilar relationship with respect to the length of header 56 as thosespecifically set forth.

The compressors and 12 are compounded and the oil is returned fromreservoir 55 in the FIGURE 2 system in essentially the same manner asdisclosed in FIG- URE 1. It Will be noted that a desuperheater 98 ispro.

vided in the pressure stream 22 from the low temperature compressor 12to the suction side of the compressor 18 rather than an inter-cooler 23shown in FIGURE 1. The refrigerant line 76 is connected to the liquidheader 30 intermediate to the supply lines 87 and 88 to normal and lowtemperature fixtures for introducing refrigerant into the desuperheaterthrough expansion valve 76A.

The air handling arrangement in the FIGURE 2 system is similar to thearrangement in the FIGURE 1 system except that condenser 34- of the airconditioning system is positioned apart from condenser 14- and is notpart of the heat reclaiming arrangement in this embodiment. Furthermore,the single evaporator 37 in the air conditioning system of FIGURE 2 isarranged with ducts and a blower for drawing and discharging air eitherinside or outside of the building.

Having fully described my invention, it is to be understood that I donot wish to be limited to the details herein set forth or the detailsillustrated in the drawings, but my invention is of the full scope ofthe appended claims.

I claim:

1. In a compound refrigeration system having a plurality of evaporatorsadapted to operate a plurality of separate and independent refrigeratedfixtures subjected to ambient and varying load conditions andmaintaining such fixtures Within the inclusive range of refrigerationtemperatures of about 50F. to about F., condenser-receiver means forsupplying liquid refrigerant to all of said evaporators, separate firstand second suction header means, at least two serially connected andcontinuously operating compressors having different suction pressures,the evaporators adapted to operate in the upper range of refrigerationtemperatures each being connected to said first suction header means,said first suction header means connected directly to the suction sideof the downstream compressor, the evaporators adapted to operate in thelower range of refrigeration temperatures each being connected to saidsecond suction header means, said second suction header means connecteddirectly to the suction side of the upstream compressor, said upstreamcompressor receiving a continuous and relatively stable load from saidevaporator-s operating in the lower range of refrigeration temperaturesto assure the continuous operation thereof and said upstream compressoradding said relatively stable load to a fluctuating load received by thedownstream compressor.

2. In a system for indicating the presence of refrigerant vapor in thecompressedcondensed refrigerant supplied to a plurality of evaporatormeans from a single receiver, the combination of: a relatively long andstraight header having its upstream end communicating with the receiver,a separate supply conduit operably connecting each evaporator means tosaid header, each of said conduits being substantially smaller incross-sectional area than said header, visual means positioned in thetwo supply conduits nearest said upstream end of the header forindicating the presence of refrigerant vapor in the conduits and audiblewarning means respon- 2% sive to a non-refrigerating condition of saidevaporator means connected to said two supply conduits nearest saidupstream end of said header.

3. The combination of claim 2 wherein said header is inclined downwardlybetween said upstream end and its downstream end.

4. A refrigeration system comprising a multitude of separate andindependent first fixtures spaced apart from each other and operatin atnormal refrigeration temperatures, a multitude of separate andindependent second fixtures spaced apart from each other and operatingat low refrigeration temperatures, said first and second fixtures beingsubjected to varying heat loads resulting from product and ambientconditions, first evaporators with at least one positioned in each ofsaid first fixtures and operating at relatively high suction pressures,said first evaporators producing a fluctuating load by reason of saidnormal temperature operation and said subjection to varying heat loads,second evaporators with at least one positioned in each of said secondfixtures and operating at relatively low suction pressures, said secondevaporators producing a continuous and stable load relative to the firstevaporator load, condenser-receiver means for supplying liquidrefrigerant to all of said evaporators, first continuously operatingcompressor means having a discharge side connected to saidcondenser-receiver means, said first compressor means having a suctionside, first suction header means connected directly between said suctionside of said first compressor means and each of the outlets of saidfirst evaporators, second continuously operating compressor means havinga suction side, second suction header means connected directly betweensaid suction side of said second compressor means and each of theoutlets of said second evaporators, and said second compressor meansoperating continuously and having the discharge side connected to saidsuction side of the first compressor means for discharging gaseousrefrigerant to said first compressor means to add the relatively stableand continuous load of said second evaporators to the fluctuating loadof said first evaporators for stabilizing the load to and maintainingcontinuous operation of the first compressor means.

5. A refrigeration system in a commercial installation comprising afirst plurality of separate and independent refrigerated fixtures spacedfrom each other and operating at normal temperatures, a second pluralityof separate and independent refrigerated fixtures spaced from each otherand operating at low temperatures, said first and second refrigeratedfixtures being subjected to ambient and varying load conditions, a firstplurality of evaporators with at least one positioned in each of saidfirst plurality of fixtures and operating at relatively high suctionpressures, said first plurality of evaporators producing a fluctuatingload by reason of said normal temperature operation, and said subjectionto ambient and load conditions, a second plurality of evaporators withat least one positioned in each of said second plurality of fixtures andoperating at relatively low suction pressures, a condenser-receivermeans for supplying liquid refrigerant to all of said evaporators, afirst compressor means having a discharge side connected to saidcondenser-receiver means, said first compressor means having a suctionside, first suction header means connected directly between said suctionside of said first compressor means and each of the outlets of saidfirst plurality of evaporators, a second compressor means having asuction side, second suction header means connected directly betweensaid suction side of said second compressor means and each of theoutlets of said second plurality of evaporators, said second compressormeans operating continuously and having the discharge side connected tosaid suction side of the first compressor means for continuouslydischarging gaseous refrigerant to said first compressor means forstabilizing the load on and maintain- 9 ing continuous operation of thefirst compressor means, and third compressor means for operating an airconditioning system of the installation and having valve controlledmeans on the suction and discharge sides thereof in fiuid communicationwith the suction and discharge sides of said first and second compressormeans for selectively substituting said third compressor means foreither said first or second compressor means.

6. A compounded refrigeration system comprising a plurality of separateand independent first fixtures spaced from each other end each havingevaporator means for the normal temperature refrigeration of said firstfixtures, a plurality of separate and independent second fixtures spacedfrom each other and each having evaporator means for the low temperaturerefrigeration of said second fixtures, said first and second fixturesbeing subjected to ambient and varying load conditions, liquidrefrigerant suppiy means including condenser-receiver means connected byliquid header means to the evaporator means of all of said first andsecond fixtures, a continuous- 1y operating first compressor meanshaving a suction side, first suction header means connected directlybetween said first compressor means suction side and the outlets of theevaporator means of all of said first fixtures, a continuously operatingsecond compressor means having a suction side, second suction headermeans connected directly between said second compressor means suctionside and the outlets of the evaporator means of all of said secondfixtures, said second compressor means having a suction pressurerelatively lower than the suction pressure of said first compressormeans, said second compressor means having a pressure side connected tothe suction side of said first compressor means, said second compressormeans operating continuously for providing a continuous and stabilizingload to said first compressor means, said first compressor meansoperating continuously for cornpressing the refrigerant vapor from saidsecond compressor means and from said first fixtures, and said firstcompressor means having a pressure side connected to saidcondenser-receiver means.

7. A compounded refrigeration system comprising a plurality of separateand independent first fixtures spaced from each other and with eachhaving evaporator means for the normal temperature refrigeration of saidfirst fixtures, a plurality of separate and independent second T turesspaced from each other and with each having evaporator means for the lowtemperature refrigeration of said second fixtures, said first and secondfixtures being subjected to ambient and varying load conditions, liquidrefrigerant supply means including condenser-receiver means connected byliquid header means to the evaporator means of all of said first andsecond fixtures, first compressor means having a suction side, firstsuction header means connected directly between said suction side of thefirst compressor means and the evaporator means of all of said firstfixtures for receiving refrigerant vapor therefrom, second compressormeans having a suction side, second suction header means connecteddirectly between said suction side of the second compressor means andthe evaporator means of all of said second fixtures for receivingrefrigerant vapor therefrom, said second compressor means having apressure side connected to the suction side of said first compressormeans, said first compressor means having a pressure side connected tosaid condenser-receiver means, each of said evaporator means havingmetering means for regulating the flow of refrigerant to said evaporatormeans to thereby produce substantially constant preset temperatures ineach of said first and second fixtures, the regulation of refrigerantflow in said evaporator means producing variations in the cumulativerefrigerant vapor loads on the suction sides of said first and secondcompressor means, and each of said compressor means operatingcontinuously for compressing and varying refrigerant vapor loads on thesuction sides thereof.

8. A compounded refrigeration system comprising a plurality of separateand independent first fixtures spaced from each other and with eachhaving evaporator means for the normal temperature refrigeration of saidfirst fix tures, a plurality of separate and independent second fixturesspaced from each other and with each having evaporator means for the lowtemperature refrigeration of said second fixtures, said first and secondfixtures being subjected to ambient and varying load conditions, liquidrefrigerant supply means including condenser-receiver means connected byliquid header means to the evaporator means of all of said first andsecond fixtures, a continuously operating first compressor means havinga suction side, first suction header means connected directly betweensaid suction side of the first compressor means and the evaporator meansof all of said first fixtures for receiving refrigerant vapor therefrom,a continuously operating second compressor means having a suction side,second suction header means connected directly between said suction sideof the second compressor means and the evaporator means of all of saidsecond fixtures for receiving refrigerant vapor therefrom, theevaporator means of each of said first and second fixtures beingsubjected to different refrigerant flow requirements in maintaining therefrigerating temperatures for each fixture, said second fixturesrequiring a more constant refrigerant flow to maintain the evaporatormeans at low refrigeration temperatures than the refrigerant flowrequired to maintain the temperatures in said first fixtures and thcumulative refrigerant vapor load from said second fixtures to saidsecond compressor means being stable relative to the fluctuatingcumulative refrigerant vapor load from said first fixtures to said firstcompressor means, said second compressor means having a pressure sideconnected to the suction side of said first compressor means anddischarging its refrigerant vapor load thereto for stabilizing the totalrefrigerant vapor load at the suction side of said first compressormeans, and said first compressor means having a pressure side connectedto said condenser-receiver means.

9. A refrigeration system in which there are a multitude of separate andindependent low temperature fixtures and a multitude of separate andindependent higher temperature fixtures with at least some of saidfixtures being spaced from each other and subjected to different andvarying loads and ambient conditions, a continuously operating firstcompressor means having a suction side header connected directly to allof the higher temperature fixtures for operation thereof, secondcompressor means having a suction side header connected directly to allof the low temperature fixtures, said second compressor means operatingcontinuously for discharging compressed refrigerant gas to the suctionside of said first compressor means and providing a continuous load thatis relatively more stable than the refrigerant load from said highertemperature fixtures, the cumulative load from said second compressormeans and said higher temperature fixtures constituting substantiallythe only load upon said first compressor means and being sufficient tomaintain continuous operation of said first compressor means, said firstcompressor means discharging the total refrigerant load to condensermeans and thence to said low and higher temperature fixtures.

10. A compounded refrigeration system comprising a plurality of separatefirst fixtures each having evaporator means for the normal temperaturerefrigeration of said first fixtures, a plurality of separate secondfixtures each having evaporator means for the low temperaturerefrigeration of said second fixtures, liquid refrigerant supply meansincluding condenser-receiver means connected by liquid header means tothe evaporator means of all of said first and second fixtures, firstcompressor means having a suction side connected to the evaporator meansof all of said first fixtures, second compressor means having a suctionside connected to the evaporator means of all of said second fixtures,said second compressor means having a pressure side connected to thesuction side of said first compressor means, said first compressor meanshaving a pressure side connected to said condenser-receiver means, thirdcompressor means having suction and pressure sides, means includingvalve controlled conduit means for selectively substituting said thirdcompressor means for either of said first and second compressor means,and air conditioning means, said third compressor means normally beingconnected to said air conditioning means and being isolated from saidfirst and second compressor means.

11. A compounded refrigeration system comprising a plurality of separatefirst fixtures each having evaporator means for the normal temperaturerefrigeration of said first fixtures, a plurality of separate secondfixtures each having evaporator means for the low temperaturerefrigeration of said second fixtures, liquid refrigerant supply meansincluding condenser-receiver means connected by liquid header means tothe evaporator means of all of said first and second fixtures, firstcompressor means having a suction side connected to the evaporator meansof all of said first fixtures, second compressor means having a suctionside connected to the evaporator means of all of said second fixtures,said second compressor means having a pressure side connected to thesuction side of said first compressor means, said first compressor meanshaving a pressure side connected to said condenserreceiver means,normally open valve means at the suction and pressure sides of each ofsaid first and second compressor means adapted to be closed forselectively isolating said first and second compressor means from saidsystem, and other compressor means having suction and pressure sideswith normally closed valve controlled means adapted to be opened forselectively substituting said other compressor means in said system forsaid isolated first or second compressor means.

12. In a refrigeration system for a commercial installation in whichthere are a plurality of separate low temperature fixtures and aplurality of separate high temperature fixtures, comprisin z a firstcompressor for operating the higher temperature fixtures, a secondcompressor for operating the low temperature fixtures and passingcompressed refrigerant gas to the inlet of the first compressor forproviding a continuous load thereon for stabilizing said firstcompressor and thence to a common condenser and thence to the fixtures;and a third compressor having an inlet and outlet for operating an airconditioner for the commercial installation and having valve controlledconduit means on the inlet and outlet thereof in fluid communicationwith the inlets and outlets of said first and second compressors forsubstituting said third compressor for either said first or secondcompressor.

13. A compound refrigeration system comprising a plurality of separatefirst fixtures each having evaporator means for the normal temperaturerefrigeration of said first fixtures, a plurality of separate secondfixtures each having evaporator means for the low temperaturerefrigeration of said second fixtures, liquid refrigerant supply meansincluding condenser-receiver means connected by liquid header means tothe evaporator means of all of said first and second fixtures, firstcompressor means having a suction side connected to the evaporator meansof all of said first fixtures, second compressor means having a suctionside connected to the evaporator means of all of said second fixtures,said second compressor means having a pressure side connected to thesuction 'side of said first compressor means, said first compressormeans having a pressure side connected to said condenseri2 compressorpressure side and the pressure sides of said first and second compressormeans respectively, and valve means in said conduit means forselectively substituting said third compressor means for either of saidfirst and second compressor means.

1d. The compound refrigeration system according to claim ll? includingan air conditioning system, said third compressor means normally beingconnected to said air conditioning system and being isolated from saidfirst and second compressor means by said valve means.

15. A refrigeration system comprising a first plurality of separate andindependent refrigerated fixtures spaced from each other and operatingat normal temperatures and subject to ambient and varying loadconditions, a second plurality of separate and independent refrigeratedfixtures spaced from each other and operating at low temperatures andsubject to ambient and varying load conditions, a first plurality ofevaporators with at least one positioned in each of said first pluralityof fixtures and operating at relatively high suction pressures, saidfirst plurality of evaporators producing a fluctuating load by reason ofsaid normal temperature operation and said subjection to ambient andvarying load conditions, a second plurality of evaporators with at leastone positioned in each of said second plurality of fixtures andoperating at relatively low suction pressures, condenserreceiver meansfor supplying liquid refrigerant to all of said evaporators, a liquidheader having an upstream end connected to said condenser-receivermeans, supply conduit means operably connecting each of the plurality ofevaporators to said liquid header downstream of said upstream end, saidupstream end of said header being at least as high as the other portionof said header, means positioned in at least one of said supply conduitmeans adjacent said upstream end of said liquid header for indicatingthe presence of refrigerant vapor in that said supply conduit means,first compressor means having a discharge side connected to saidcondenser-receiver means, said first compressor means having a suctionside, first suction header means connected directly betweetn each of theoutlets of said first plurality of evaporators and the suction side ofsaid first compressor means, second compressor means having a suctionside, second suction header means connected directly between each of theoutlets of said second plurality of evaporators and the suction side ofsaid second compressor means, and said second compressor means havingthe discharge side thereof connected to said suction side of the firstcompressor means and operating continuously for discharging gaseousrefrigerant to said first compressor means for stabilizing therefrigerant load to said first compressor means for maintainingcontinuous operation of the first compressor means.

16. A refrigeration system comprising a first plurality of separate andindependent refrigerated fixtures spaced from each other and operatingat normal temperatures and subject to ambient and varying loadconditions, a second plurality of separate and independent refrigeratedfixtures spaced from each other and operating at low temperatures andsubject to ambient and varying load conditions, a first plurality ofevaporators with at least one positioned in each of said first pluralityof fixtures and operating at relatively high suction pressures, saidfirst plurality of evaporators producing a fluctuating load by reason ofsaid normal temperature operation and said subjection to ambient andvarying load conditions, a second plurality of evaporators with at leastone positioned in each of said second plurality of fixtures andoperating at relatively low suction pressures, condenserreceiver meansfor supplying liquid refrigerant to all of said evaporators, a singlestraight liquid header having an upstream end connected to saidcondenser-receiver means, a plurality of supply conduits connecting saidevaporators to said liquid header, said liquid header having theupstream end at least as high as any other por- '13 tion of the liquidheader, said first and second plurality of refrigerated fixturescontaining products having varying sensitivity to temperature variationsfrom the desired product temperature, said fixtures containing productsleast sensitive to temperature variations having the evaporatorspositioned therein connected by said supply conduits to the furthestupstream locations on said liquid header, said fixtures containingproducts most sensitive to temperature variations having the evaporatorspositioned therein connected by said supply conduits to the furthestdownstream locations on said header, first compressor means having adischarge side connected to said condenser-receiver means, said firstcompressor means having a suction side, first suction header meansconnected directly between each of the outlets of said first pluralityof evaporators and the suction side of said first compressor means,second compressor means having a suction side, second suction headermeans connected directly between each of the outlets of said secondplurality pressor means, and said second compressor means having thedischarge side thereof connected to said suction side of the firstcompressor means and operating continuously for discharging gaseousrefrigeration to said first compressor means for stabilizing therefrigerant load to said first compressor means for maintainingcontinuous operation of the first compressor means.

References Cited by the Examiner UNITED STATES PATENTS 2,024,323 12/1935Wyld 62-510 2,054,542 9/1936 Hoelle 62-126 2,067,638 1/1937 Homaday62-129 2,418,962 4/1947 ZWiCkl 62-470 2,439,331 4/1948 Bean 62-1292,585,908 2/ 1952 Backstrom 62-510 2,841,962 7/1958 Richards 62-2783,150,498 9/1964 Blake 62-81 MEYER PERLIN, Primary Examiner.

ROBERT A. OLEARY, Examiner.

1. IN A COMPOUND REFRIGERATION SYSTEM HAVING A PLURALITY OF EVAPORATORSADAPTED TO OPERATE A PLURALITY OF SEPARATE AND INDEPENDENT REFRIGERATEDFIXTURES SUBJECTED TO AMBIENT AND VARYING LOAD CONDITIONS ANDMAINTAINING SUCH FIXTURES WITHIN THE INCLUSIVE RANGE OF REFRIGERATIONTEMPERATURES OF ABOUT 50* F. TO ABOUT -20* F., CONDENSER-RECEIVER MEANSFOR SUPPLYING LIQUID REFRIGERANT TO ALL OF SAID EVAPORATORS, SEPARATEFIRST AND SECOND SUCTION HEADER MEANS, AT LEAST TWO SERIALLY CONNECTEDAND CONTINUOUSLY OPERATING COMPRESSORS HAVING DIFFERENT SUCTIONPRESSURES, THE EVAPORATORS ADAPTED TO OPERATE IN THE UPPER RANGE OFREFRIGERATION TEMPERATURES EACH BEING CONNECTED TO SAID FIRST SUCTIONHEADER MEANS, SAID FIRST SUCTION HEADER MEANS CONNECTED DIRECTLY TO THESUCTION SIDE OF THE DOWNSTREAM COMPRESSOR, THE EVAPORATORS ADAPTED TOOPERATE IN THE LOWER RANGE OF REFRIGERATION TEMPERATURES EACH BEINGCONNECTED TO SAID SECOND SUCTILN HEADER MEANS, SAID SECOND SUCTIONHEADER MEANS CONNECTED DIRECTLY TO THE SUCTION SIDE OF THE UPSTREAMCOMPRESSOR, SAID UPSTREAM COMPRESSOR RECEIVING A CONTINUOUS ANDRELATIVELY STABLE LOAD FROM SAID EVAPORATORS OPEATING IN THE LOWER RANGEOF REFRIGERATION TYEMPERATURES TO ASSURE THE CONTINUOUS OPERATIONTHEREOF AND SAID UPSTREAM COMPRESSOR ADDING SAID RELATIVELY STABLE LOADTO A FLUCTUATING LOAD RECEIVED BY THE DOWNSTREAM COMPRESOR.